An analog-to-digital converter (ADC) is a device that takes an analog input signal (e.g., VIN) and converts it into an N-bit digital signal (e.g., dN-1 . . . d0). The resulting N-bit digital signal is associated with a discrete quantized version of the analog input signal. In some instances, the quantization of the analog input signal is provided in a coded form such as binary coded decimal (BCD).
ADCs may employ a wide variety of architectures, such as integrating, successive-approximation, flash, and delta-sigma architectures. In general, the process of analog-to-digital conversion starts with sampling the analog input signal at some periodic rate. Each sample of the analog input signal is typically evaluated by comparing the sampled analog input signal to one or more reference signals. The differences between the reference signals and the sampled analog input are evaluated by comparator circuits, whose outputs are processed by a digital encoder circuit.
An ADC is a key building block in many mixed-mode integrated circuits (ICs). Once the analog signal is converted into the digital domain, complicated signal processing functions can be performed with easier handling and improved noise immunity. In one instance, the digital signals are stored as in a data-logging function. In another instance, the stored digital signals are processed to provide digital signal processing functions, or some other numerical analysis.